The present invention relates to an Ethernet, and more particularly, to an Ethernet having an automatic detecting function of data transfer rate to efficiently manage the Ethernet.
Generally, the Ethernet monitors lines during data transfer between stations and transfers data only when a network is not busy. Here, when the transferred data of one station interferes with that of another station, the Ethernet recognizes the transfer failure and retries the data transfer to complete communication.
Thus, to reduce such collision, the occupation or busy status of a channel is detected prior to initiating the data transfer and the data transfer is delayed at least until a current carrier is available or in other words a busy signal disappears. Since a controller transferring the data can simultaneously receive the data being transferred by itself, interference can be quickly detected by comparing the transferred data and the received data.
Referring to FIG. 1, a conventional Ethernet will now be described.
The conventional Ethernet comprises a medium access controller 1 for controlling 10 Mbps/100 Mbps Ethernet protocol, an encoder/decoder 2 for encoding NRZ (Non-Return to Zero) data to Manchester data corresponding to a data transfer rate during transceiving and decoding of the Manchester data to NRZ data, and a data transceiver portion 3 for transmitting the encoded data by adjusting a data level according to the characteristics of a communication medium, i.e., paper tape, cards, and magnetic tape, and transferring the data received from the communication medium to a decoder block of the encoder/decoder 2.
In a conventional Ethernet with such structure, a 10 Mbps or 100 Mbps control signal is generated by an internal register of the medium access controller 1 by software or hardware. When selecting a mode by software, a set-up program and an external E.sup.2 PROM can be used as a setting method. When the mode is selected by hardware, a user can select the mode by manipulating select pins for 10 Mbps and 100 Mbps.
First, when the 10 Mbps mode is selected, a medium access controller 1 enables 10 Mbps data transceiving paths of encoder/decoder 2 and data transceiver 3, and disables 100 Mbps data transceiving paths. Accordingly, when transmitting, data to be transferred to the communication medium via a host interface is input into the medium access controller 1, and data frame operation is performed in the medium access controller 1 in accordance with the transfer protocol.
When the data to be transferred to the communication medium is ready, the data is then transferred to a 10 Mbps encoder block of the encoder/decoder 2. The 10 Mbps encoder block encodes the data according to the transfer protocol of the communication medium and outputs the encoded data to a 10 Mbps transmitting block of the data transceiver 3. Next, the 10 Mbps transmitting block receiving the encoded data adjusts the data level according to the transfer characteristics of the communication medium and transfers the data to the communication medium.
In the meantime, for 10 Mbps data receiving, data of the communication medium is received by a 10 Mbps receiving block of the data transceiver 3. The 10 Mbps receiving block converts the data to be suitable for data decoding in a 10 Mbps decoder block of the encoder/decoder 2 and transfers the converted data to the 10 Mbps decoder block. The 10 Mbps decoder block decodes the transferred data from the 10 Mbps receiving block along with a sync clock signal and a receiving enable signal and transfers the decoded data to the medium access controller 1.
Here, medium access controller 1 analyzes a frame of the transferred data and determines which data among the data received from the communication medium is received by itself, that is, data corresponding to an intrinsic address of the medium access controller 1. The data determined to be received by that particular medium access controller 1 is transferred from the communication medium along with an intrinsic address designating the location for accessing that data. Thus, only data with intrinsic address of the medium access controller 1 is received and the received data is transferred through the host interface.
On the other hand, when the 100 Mbps mode is selected, similar to the case when 10 Mbps mode is selected, the medium access controller 1 enables 100 Mbps data transceiving paths of encoder/decoder 2 and data transceiver 3, and disables 10 Mbps data transceiving paths.
However, in a conventional Ethernet, a user needs to construct and set up a control signal for mode selection by software or hardware according to the receiving signal rate. Thus, when an installer constructing the network or a user does not know the receiving signal rate, the control signal set-up is rendered impossible.